1. Technical Field
The present invention relates to a method of manufacturing a liquid ejecting head, a liquid ejecting head, and a liquid ejecting apparatus and, more particularly, to a method of manufacturing an ink jet recording head for ejecting an ink as a liquid, an ink jet recording head, and an ink jet recording apparatus.
2. Related Art
In an ink jet recording head which is a representative example of a liquid ejecting head generally, ink from an ink cartridge in which the ink is reserved is supplied to nozzle openings via an ink supply needle inserted into the ink cartridge and a channel and the ink is ejected from the nozzle openings by driving a piezoelectric element.
As such a piezoelectric element, for example, use of deflection deformation of a piezoelectric element including a lower electrode, a piezoelectric layer and an upper electrode is put to practical use. As a piezoelectric element of a deflection vibration mode, a technique of relaxing tensile stress applied from a substrate such as a vibration plate to a piezoelectric element by adjusting the film thickness of the lower electrode of the piezoelectric element is suggested (for example, JP-A-2002-164586). In addition, the piezoelectric layer of such a piezoelectric element is formed with a predetermined thickness by laminated piezoelectric films, by repeatedly performing a process of heating a piezoelectric precursor film with a heater so as to perform crystallization and form a piezoelectric film plural times.
However, the piezoelectric element of the deflection vibration mode is deformed in a short side direction (widthwise direction) when a voltage is applied, but the deformation thereof in a longitudinal direction is restricted by a vibration plate. Accordingly, when the voltage is applied, the piezoelectric element receives a strong tensile stress in the longitudinal direction from the vibration plate, and cracks occur in the piezoelectric layer along the widthwise direction of the piezoelectric element due to the tensile stress, and thus the piezoelectric element is broken.
Such tensile stress occurs due to the process of heating the piezoelectric layer so as to perform crystallization and then cooling the piezoelectric layer. That is, compression stress occurs in the piezoelectric layer due to the cooling, but the deformation is restricted by the vibration plate as described above. Accordingly, the piezoelectric element receives tensile stress from the vibration plate and thus cracks occur in the piezoelectric element from the tensile stress.
In the piezoelectric element according to JP-A-2002-164586, in particular, the relaxation of the tensile stress received from the vibration plate in the longitudinal direction is not sufficient, and the film thickness of the lower electrode configuring the piezoelectric element is adjusted. Accordingly, a manufacturing process is troublesome.
Such a problem occurs in not only an ink jet recording head unit but also a liquid ejecting head unit for ejecting a liquid other than the ink.